Projection system and method of curved film

ABSTRACT

The invention involves a sort of curved film projection system, including a rendering surface, a projection screen, a real scene rendering model of image system, a rendering model of projection system that renders the projection the image rendered by the rendering model of image system on the rendering surface, and projecting devices that projects the image finally rendered by the rendering model of projection system onto the projection screen through optical lens. The viewing direction and angle from observer&#39;s eyes to the rendering surface is consistent with that to the projection screen. The image system rendering model can be reversible on optical path with the projection system rendering model. The curved film projection system not only reduces the rendering cost, but also produces lifelike experience for audience.

FILED OF THE INVENTION

The invention involves digital film technique, to be specific, a sort ofoptics technique together with computer graph technique, recorded indigital or some other regular ways, so as to generate a device systemthat can really restore 3D effects by projecting image on curved screen.

BACKGROUND OF THE INVENTION

3D movie brings forward a lifelike experience. As stated by thepioneering 3D movies principle, when people watch with eyes, distanceand 3D effect are engendered by eye angel, thus when two eyes aim atsame object, the visual angle is different. The closer the object, themore different the view filed of two eyes, vice versa, the less; and itis almost paralleled looking into far distance. 3D movie principlenamely two cameras shoot at the same time simulating human eyes,projecting to the same screen in synchronization, therefore 3d effect isproduced with different views of the two eyes separated by polarizedglasses.

The principle to make 3d movie by adopting curved screen: a fewparameters need to be explained concerning optical characters of humaneyes: horizontal coverage of human eye is around 150°, vertical coverageis around 55°. The best viewing angle is: around 10° up and down theviewing field, 10° for horizontal direction. The distance of the twopupils is 55˜74 mm. Viewing angle around 55° is similar with human eyes.Perspective effect of projected image at this angle conforms with thatof human eyes, real and natural. FIGS. 1 & 2 are viewing field andviewing angle diagram of human eyes. Eyes will move around with headwhen looking around, as shown on FIGS. 3 & 4. The existing 3D movieproduction technique normally simulates spherical or curved surface withmultiple planes, wherein the produced image is not seamless, smooth orcontinuous and can only be applicable to such simple geometrical modelsas sphere and conicoid. If applicable to 3d model, the parallax can notturn to be smooth and continuous. The curved surface can also besimulated with the optical ray tracing method under present technique.But the rendering cost is very high.

SUMMARY OF THE INVENTION

The purpose of the invention is to put forward a kind of curved filmprojection system to improve the existing technique.

Technical solution the invention adopts aims to create a sort of curvedfilm projection system, comprising

a rendering surface,

a projection screen,

a real scene rendering model of image system,

a rendering model of projection system that renders the projection theimage rendered by the rendering model of image system on the renderingsurface, and

a projecting device that projects the image finally rendered by therendering model of projection system onto the projection screen throughoptical lens.

The said projection screen is regarded as the first surface or part ofthe first surface. The said rendering surface is regarded as the secondsurface or part of the second surface. The first surface is behind thesaid second surface, watching from observer's eyes to projection screen.The viewing direction and angle from observer's eyes to the renderingsurface is consistent with that to the projection screen. The viewingdirection and angle from observer's eyes to the rendering surface isconsistent with that to the screen; the said image system renderingmodel can be reversible with the said projection system model. The saidrendered real scene by projection system rendering model, projected tothe second surface and then to the projection screen through projectingdevice, exactly restore the distorted image produced by the image systemrendering model.

The rendering models of both image system and projection systemrespectively comprise cameras and projectors, the view directions ofwhich are consistent, two centers coincide, but the optical paths arereversible.

The curved film projection system is characterized that the image systemrendering model comprises up-and-down M-layer digital cameras and eachlayer contains N cameras.

In the preferred embodiment, the said M is 3, the said N is 7, the saidimage system rendering model contains 21 single digital cameras. Theangle of the horizontal view field of each digital camera is25.7142857°, and the angle of vertical view field is 60°. The viewingdirection of all digital cameras follow the same direction as that ofthe divided viewing field. Horizontal viewing direction of each camerais 12.8571°, 38.5714°, 64.2857°, 90°, 115.7143°, 141.4286° and 167.1429°respectively.

In another alternate embodiment, the said M is 3, the said N is 3, thesaid image system rendering model contains 9 single digital cameras. Theangle of horizontal view field of each camera is 60°. The angle ofvertical view field is 60°. Viewing direction of all digital camerasfollow the direction of divided viewing field. The horizontal viewingdirection of each single digital camera in each layer is 30°, 90° and150° respectively.

The projection system rendering model comprises upper and lower M-layerdigital cameras, each layer of which contains N single digitalprojectors.

In a preferred embodiment, the said M is 3, the said N is 7, the saidprojection system rendering model contains 21 single digital cameras.The angle of horizontal view field of each projection system renderingmodel is 25.7142857°, and the angle of vertical view field is 60°. Theviewing directions of all digital projectors are the same as dividedviewing field. Horizontal viewing direction of each projector in eachlayer is 12.8571°, 38.5714°, 64.2857°, 90°, 115.7143°, 141.4286° and167.1429° respectively.

In anther alternate embodiment, the said M is 3, the said N is 3, andthe said projection system rendering model contains 9 cameras. The angleof horizontal view field of each projector is 60°. The angle of verticalview filed is also 60°. Viewing direction of all digital projectors arethe same as that of divided viewing field. The horizontal viewingdirection of each digital projector in each layer is 30°, 90° and 150°respectively.

The said first surface of the curved film projection system is a curvedsurface, a plane surface, or a combination of plane and curved surface.The said second surface is sphere or conicoid.

Set a spherical surface, take the vertical section of the sphere, whichis round in shape, the said vertical axis of the section is OZ, dividehorizontal viewing field 0˜180° of the section into n parts, indicatethe n viewing directions with radial OA1˜OAn, divide the said semicirclediameter evenly into n parts with section points as P0, P1, P2 . . .Pn-1 and Pn, draw n lines as L1, L2, L3 . . . Ln-1 and Ln paralleled toOZ axis cross the said n section points, then followed with in turn M1,intersection point of OA1 and L1, M2, intersection point of OA2 and L2,M3, intersection point of OA3 and L3 . . . Mn-1, intersection point ofOAn-1 and Ln-1, Mn, intersection point of OAn and Ln, connect M0, M1, M2. . . Mn-1 and Mn to get a curve K, rotate curve K 360° around OZ axisto get curved surface B, the said second surface is curved surface B.

The invention adopts a technical solution of curved film projectionmethod which is characterized in following steps:

A1) the rendering model of image system rendering the real scene.

A2) the rendering model of projection system rendering the projection ofimage rendered by the image system rendering model on the renderingsurface.

A3) the projecting device projecting the finally rendered image of therendering model of projection system onto the projection screen via theoptical lens.

The rendering as mentioned in above A2) adopts orthogonal rendering.

The application of curved film projection system avails as follows: theadoption of spherical rendering model based on optical pathreversibility principle vividly restores ubiety of space project; theimage turns to be totally seamless, smooth and continuous that canexactly restore spherical surface and conicoid; the parallax could bemade smooth and continuous under 3D mode by application of curvedsurface that either can be or not be described in mathematic model,which bring the audience a lifelike experience. The rendering cost couldbe decreased considerably accordingly by introducing a simplifieddigital optical lens model into this curved film projection system.

BRIEF DISCIRPTION OF THE DRAWINGS

The features and advantages of the present invention will becomeapparent form the following detailed description of the invention whenread with the accompanying drawings in which:

FIG. 1 is a side view of viewing field and visual angle of human eyes;

FIG. 2 is a plane view of viewing filed and visual angel of human eyes;

FIG. 3 is a schematic diagram of the scene viewed when human eyes lookup and down;

FIG. 4 is a schematic diagram of the scene viewed when human eyes lookleft and right;

FIG. 5 is a schematic diagram of 0˜180° continuous integral of viewingfield 0˜180°

FIG. 6 is a diorama mapped plane on spherical surface from ahead

FIG. 7 is a diorama mapped side elevation on spherical surface fromahead

FIG. 8 is a mapped perspective on spherical surface from ahead

FIG. 9 is a side elevation of simplified digital model for sphericalscreen calculation;

FIG. 10 is a plane view of simplified digital model for spherical screencalculation;

FIG. 11 is a perspective of simplified digital model for sphericalscreen calculation;

FIG. 12 is a side elevation of optical path of spherical screen;

FIG. 13 is a plane view of optical path of spherical screen;

FIG. 14 is a schematic diagram of optical lens model used for sphericalscreen system;

FIG. 15 is a schematic diagram of spherical screen, optical lens andimage system;

FIG. 16 is a schematic diagram of anchor point of spherical surface;

FIG. 17 is a schematic diagram of spherical surface imaging throughoptical lens;

FIG. 18 is a schematic diagram of spherical surface imaging throughcommon digital lens;

FIG. 19 is an imaging comparison diagram of through optical lens andcommon digital lens;

FIG. 20 is a schematic diagram of reversibility principle of opticalpaths;

FIG. 21 is a plane view of computer rendering overall model

FIG. 22 is a side elevation of computer rendering overall model

FIG. 23 is a perspective of overall model rendering;

FIG. 24 is a systematic overview of computer rendering image system;

FIG. 25 is a schematic diagram of one of the 7 cells when sphericalsurface intersected along meridian

FIG. 26 is a schematic diagram of three cases when spherical surfaceintersected along meridian;

FIG. 27 is a schematic diagram of rendering image of spherical surface uunit in computer;

FIG. 28 is a schematic diagram of rendering image of spherical surface munit in computer;

FIG. 29 is a schematic diagram of rendering image of spherical surface dunit in computer;

FIG. 30 is a systematic overview of computer rendering projectionsystem;

FIG. 31 is a diagram of projected range onto spherical surface of uunit;

FIG. 32 is a diagram of projected range onto spherical surface of munit;

FIG. 33 is a diagram of projected range onto spherical surface of dunit;

FIG. 34 is a schematic diagram of hemispherical orthogonal rendering;

FIG. 35 is the mathematical model of digital optical lens;

FIG. 36 is the rendering model of digital optical lens;

DETAILED DESCRIPTION OF THE INVENTION

By adopting optical paths reversibility, to realize restoration of spaceobject ubiety through spherical rendering model, the produced image ofthe invention turns to be totally seamless, smooth and continuous, whichis applicable to spherical surface, conicoid, or curved surface that caneither be described or not in mathematic model. The parallax can be madesmooth and continuous in 3D mode. Curved surface can also be simulatedwith calculation of optical ray tracing method, which is costly,comparatively simplified model is substantially savable.

Suppose human eyes at the same level, set a simple analogue as shown onFIG. 5 to simulate the view range when human eyes look around. Asindicated, if C is supposed to be a source point, line out in somedirection an infinitesimal solid angel dω, corresponding to ds, asection of the spherical surface, the spherical radius as r, then thefollowing relation is brought up: dω=ds/r², the solid of entire spaceω=4π sterad, is the continuous integral of human eye viewing field. Inorder to represent the real screen ahead of eyes, suppose all realobjects has a projection on spherical surface with eyes as the center ofthe circle, when image recorded at eyes position, then projected to thesame spherical surface, a real scene can be experienced when lookingfrom the center of the sphere as shown on FIGS. 6,7 and 8. As indicatedon FIGS. 6 and 7, if such space objects as offing, ship, plane andbridge have a projection on the spherical surface with eye as the centerof the circle, a real scene can be felt at the correct location from theprojection. The basic principle of the invention is to record the sceneviewed from audience eyes location, view field and viewing angle, andthen project to one section of spherical surface with eyes as center ofthe circle. Audience can feel the viewed scene restored when watchingfrom effective position. The projected image may be actually shot, butthe simulation limited by equipment conditions (such as hoist, bracket,gliding rail or any other walking equipments), what can be caught areonly browed scenes or flying scenes; restricted with browse equipmentsor flight safety, many extreme shrilling pictures cannot be caught. Sothis is an option for low cost production.

Computerized production is also viable, whose carrier can be film, videotape, disk, hardware or other digital removable disk storage device. Toensure the image correctness projected onto the screen, thecharacteristic of projector optical lens should be got acquainted. It isextraordinarily costly to realize the rendering by setting up lensanalogue and material character in computer as every extra wide anglelens has very complicated characteristics of analogue and materialcharacter. Otherwise the image is very limited if projection is donewith actually shot image.

The preferred embodiment of the invention is to record the scene viewedfrom audience eyes' location, viewing field and viewing angle, and thenproject to one section of spherical surface with eyes as center of thecircle. When watching from effective position, audience can feel theviewed scene restored. Optical paths of spherical screen model is asshown on FIGS. 12 & 13, the indicated camera lens should be providedwith extra wide angle ranging 0˜160°, characterized with viewing fieldcontinuously and evenly distributed. The projector lens should beespecially designed optical type, with extra wide angle lens made by anymanufacturer in the world, similar with the model as indicated on FIG.14, both are center system of spherical surfaces.

FIG. 15 gives the detailed description on relation of spherical screen,optical lens, imaging surface, definite object and object on imagingsurface. It goes in two steps: firstly, without spherical screen, realimage N′N is produced image of edifice M′M on imaging surface transitingoptical lens; secondly, laying a spherical surface in front of opticallens, an image P′P will be produced when real image N′N is projectedonto the spherical surface. When observer watches image P′P in front ofthe lens, he could sense the true building M′M, this is because theheight of viewing field direction, viewing angle and observing point arecertified to be highly uniform, as well the perspective relation iscertified to be correct. Some data can be obtained through analysis onthe experimental shot real image, which are taken as design reference ofdigital optical lens.

Mark an anchor point on spherical surface as shown on FIG. 15. Definethe anchor point in this way: divide longitude and parallel into nparts, the intersection points of the divided parts as shown on FIG. 16are the marked anchor points. Shoot the real image of the sphericalsurface formed on the imaging surface with the system shown on FIG. 15.As shown on FIG. 17, the one in use is extra wide angle optical lens163° and 17 mm, many marked anchor points are clearly indicated. If theshot real image is projected back onto the screen, they will becorrespondingly superposed with the marked anchor points one by one. Setcommon digital camera with same parameter as extra wide angle opticallens, namely 163°, set model in computer as shown on FIG. 15, sphericalsurface production and marked anchor point as shown on FIG. 16, whencommon digital camera takes place of optical lens and imaging surface asshown on FIG. 15, the image produced hereby from the rendering as shownon FIG. 18, is obviously different from that by optical lens. Theimaging character of special optical lens as analyzed on FIG. 17 showsthat it is impossible for any practically applied special extra wideangle lens to reach 180°, because 180° represent infinity viewpoint inhorizontal or vertical direction and fails to be imageable on imagingsurface. But X1, X2, M0, Y1 and Y2 on FIG. 17 can infinitely reach theinfinity in horizontal, front and vertical direction, that is X1-M0-X2represent an infinite line along horizontal direction, Y1-M0-Y2 is aninfinite line along vertical direction.

As indicated on FIG. 17, the rendered image on imaging surface of markedanchor point on spherical surface is evenly distributed on a circularsurface, the center of the circle, the center of the sphere and thecenter of special optical lens are completed superposed, whichpredicates that the viewing field of front hemisphere, with center oflens as origin, is evenly divided, approaching schemed perfect image. Ifcertain object located within the hemisphere in front of lens, and kepta certain distance from lens center line, its image may obtain an imageabout its same size on imaging surface, free of picture distortion.

The imaging character of common digital extra wide angle lens as shownon FIG. 18: the closer to the viewing field direction perpendicular tolens center line, the more distorted of the image. Its deficiency isthat the object has a smaller effective imaging area near lens centerline. As the important viewing area, the small area fails to supportsufficient image resolution.

FIG. 19 is the imaging contrast by adopting optical lens and commondigital lens. Image produced through common lens will lead to picturedistortion. One purpose of this invention is to create a simplifieddigital lens model provided with the same optical character as specialoptical lens, therefore calculated amount is accordingly reduced,rendering cost is lowered down as well. The detailed solution will bementioned in the following introduction.

As indicated on FIG. 9, as human eyes are at the same level, camera withfield angle 60° can realize true reflection of human eye perspective.Thus view field ranging 0˜180° up and down is divided into 3 parts, eachof which is 60°. The effect when human eyes look around the scene can besimply simulated with 3 cameras with field angle 60°. Due to pupillarydistance 55 mm˜74 mm, when looking around scene ranging 0˜180°,continuous parallax variation will be engendered, that is, the viewingscene is slightly different from each eye. Jump of viewed image throughhuman eyes projected by camera is uncomfortable. Therefore inconsideration of the best viewing field, taking larger value at 20°position, the horizontal continuous viewing field ranging 0˜180° issimulated in 7 viewing directions, the minimum quantity of view fieldcontinuity as shown on FIG. 10. The consecutive viewing direction infront of audience ranging 0˜180° is simulated in 7 horizontal and 3vertical viewing directions, totally 3×7=21 directions, so that imagejump cannot be felt, in the mean time viewing field integral model isgreatly simplified, as shown on FIG. 11.

The said digital lens model of invention is not common type, but analgorithm model composition of many computer graphs, which is more likea rendering image algorithm. The final imaging effect is almost the samewith imaging effect of the specified extra wide angle optical lensmentioned in the invention. The said digital lens model in the graphicssoftware can be represented as two rendering model. The first model isto simulate image of hemispherical scene ranging 0˜180° in front ofhuman eye; the second model is to correspondingly project images seriesshot by the first one to a special calculated curved surface. The imagedobtained when the curved surface is perpendicularly rendered is almostsimilar to that projected by special optical lens.

The following is emphasized on elaboration of digital lens model of theinvention: first goes with reversibility of optical paths. As shown onFIG. 20, either three centers and center lines of human eyes, camera andprojector are superposed. When two radials sent by object M′M in frontof human eyes are shot and then projected by projector with same angle,putting a screen on optical paths at this time, an image m′m cast ontothe screen by projector, which superposes with M′M observed from humaneyes. If it is plane image, human eyes will verdict the object distancethrough perspective. When it comes to 3d image, human eyes will positionthe object precisely, which is so called reversibility of optical paths.

The most important part of the invention is two rendering modelsdescribed above. As indicated on FIGS. 21, 22 and 23, the systematicgeneral diagram includes two rendering models, image system renderingmodel and projection system rendering model. Either image system orprojection system, each includes three layers cameras or projectors,each layer has 7 cameras or projectors, that is to say, the wholerendering model comprises 21 cameras and 21 projectors, each of which isidentical in viewing field direction and every center of whichsuperposes at center of hemispherical surface. Camera unit and projectorunit can be taken as two units same in parameter, but completelyreversible in beam radiation. Camera and projector together completelight energy transfer in reciprocal way by receiving and projectingradial. Their parameters are as follows: horizontal view field angle:180°÷7=25.7142857°; vertical view field angle: 60°; the three layers isindicated with u, m, d; horizontal 7 directions are indicated with 01,02, 03, 04, 05, 06 and 07, camera is C, projector is P, they relates asfollows:

Upper Camera Cu01 Cu02 Cu03 Cu04 Cu05 Cu06 Cu07 layer No. Projector Pu01Pu02 Pu03 Pu04 Pu05 Pu06 Pu07 No. Middle Camera Cm01 Cm02 Cm03 Cm04 Cm05Cm06 Cm07 layer No. Projector Pm01 Pm02 Pm03 Pm04 Pm05 Pm06 Pm07 No.Lower Camera Cd01 Cd02 Cd03 Cd04 Cd05 Cd06 Cd07 layer No. Projector Pd01Pd02 Pd03 Pd04 Pd05 Pd06 Pd07 No.

Projector with 01 postfix in the three layers is defined as Group 01,those with 02 is defined as Group 02 . . . 7 groups altogether from01˜07. Vertical view field of layer u, m and d is as shown on FIG. 22: uis +60, m is 0°, d is −60°. Horizontal viewing field direction of group01˜07 are as shown on FIG. 21:

Group 01 02 03 04 05 06 07 Horizontal 12.8571° 38.5714° 64.2857° 90°115.7143° 141.4286° 167.1429° viewing field direction

FIG. 23 is general perspective drawing of computer rendering model. Theimage system rendering model and projection system rendering model willbe expounded separately. What image system rendering model do is tosimulate hemispherical area scene when human eyes look around in thefront ranging 0˜180°, rendering the viewed image in 21 viewing fielddirections, continuity simulating of viewing field variation. FIG. 24indicates general diagram of computer rendering image system.

FIG. 25 indicates one of the 7 units intersected along longitudedirection with center of the sphere as the center, mainly one unit ofintersected view field in vertical direction, which is composed of 3cameras. FIG. 26 indicates three types of intersection along paralleldirection, vertical 180° area is divided into parts of u, m and d,vertical view field angle of each is 60°, 25.7142857° in horizontal.

FIGS. 27, 28 and 29 indicates image of upper, middle and lower part ofspherical surface rendered by digital camera, amongst of which theshadowed part is the effective rendered coverage, O point is viewingfield center. As computer graphics software can only rendering planeimage, only the mapping of the sphere onto the palne surface can berendered. The rendered image is very similar with that viewed by humaneyes. The vertical viewing field angle is 60°, 25.7142857° inhorizontal. The proportion of image width andheight:width:height=25.7142857:60=0.428571:1

Ratio of height and width in computer graphics software is indicatedwith resolution. So rendering image resolution of u, m and d should be429×1000 or its multiple, for instance: n(429×1000), n as multiplecoefficient. Computer rendering image system can produce as much as 21images (7 images in each of upper, middle and lower layers) bysimulating viewed effect of human eyes. The all produced imagesatisfying n 429×1000), one-to-one corresponding to projector.

What projection system rendering model to do is to project renderedimages produced by image system onto spherical surface one-to-onecorrespondingly, and optical paths reversibility should be assured, thatis, the image should be seamed in perfection by projection system ontospherical surface.

FIG. 30 is general diagram of projection system rendering model, asindicated projection unit are one-to-one corresponding to imaging unitsof image system. u, m and d image rendered by image system as shown onFIGS. 31, 32 and 33, are projected to the corresponding area on curvedsurface through projection system. To ensure the reversibility ofoptical paths, projection unit of projection system should be providedwith following optical characters: vertical view field angle=60°;horizontal view field angle=25.7142857°, only under this condition, canthe projection units of projection system be regarded reversible withimaging unit of image system, and this reversibility is the key point ofthe invention. The cited optical character is just a preferredembodiment.

FIG. 34 indicated the orthogonal rendered image of a hemisphere incomputer graphics software, which is a synthetic image rendered by 21digital camera lenses. Obviously the picture is deformed, the middlestretched, two sides compressed, as shown on FIG. 17, which is differentfrom the symmetrical graphics obtained through optical lens. What theinvention to solve is to restore image, which enable the image renderedthrough digital lens to be the same as that through optical lens. Theinvention fabricate a curved surface, on which image of sphericalsurface is perfectly projected, the obtained image in the curved surfacebeing orthogonal rendered is the same as that through optical lens.

FIG. 35 indicates how to make the curved surface in computer graphicssoftware. Divide viewing field horizontal range 0˜180° into n parts,indicated with OA1˜OAn, as shown on FIG. 35. Divide spherical diameterevenly into n parts as P0, P1, P2 . . . Pn-1, Pn, make n parallelsparalleled to OZ axis as L1, L2, L3 . . . Ln-1, Ln, which representorthogonal view field distribution. Determine in turn intersection pointM1 between OA1 and L1, M2 between OA2 and L2, M3 between OA3 and L3 . .. Mn-1 between OAn-1 and Ln-1, Mn between OAn and Ln, join M0, M1, M2 .. . Mn-1 and Mn, to get a curved line, as shown on FIG. 35, which iscalled curve K.

Curve K is not a focal conic due to without focus. Intersection pointM0, M1, M2 . . . Mn-1, Mn, made when curve K intersected by n radialsnamely OA0, OA1, OA2 . . . OAn-1, OAn sent from O point, is actuallyprojection of n radials by dividing 0˜180° horizontal view field. Whenprojection M0, M1, M2 . . . Mn-1, Mn is orthogonally cast ontosemicircle diameter, point mapping is acquired as P0, P1, P2 . . . Pn-1,Pn, which divide the diameter into n parts. Therefore horizontal 0˜180°viewing field can be divided onto a horizontal line. Rotate curve Karound OZ axis as shown on FIG. 35, a curved surface B, namely renderingsurface will be engendered, as shown on FIG. 36. The curved surface ischaracterized as follows: when projection system project radial onto thesurface, if orthogonally rendered, an image will be obtained similarwith the one when hemispherical surface is rendered through specifiedoptical lens, that is to say, optical paths reciprocal conversion iscompletely realized.

FIG. 36 indicates the final rendering model through digital opticallens. Camera resolution is set to be 4096×3592 at orthogonal rendering.The calculation of which is relative to projecting equipment of 70 mmand 10 apertures, which is the preferred embodiment of the invention.

In consideration of further cost reduction, part numbers of horizontalviewing field can be small, to the minimum 3 parts, another optionalembodiment of the invention: by adoption of 3 viewing field directionseither in horizontal or vertical, that is 3×3=9 viewing field direction,to simulate continuous viewing field direction ranging 0˜180° in frontof audience. The image system rendering model corresponding of theembodiment includes three layers of cameras, each layer of which include3 cameras. The projection system rendering model is one to onecorrespond with the image system rendering modem. The projection systemrendering model also includes three layers of projectors, each layer ofwhich include 3 projectors. Tthe viewing direction of both projectorsand cameras are consistent, centers completely superposed, optical pathsreversible. Horizontal view field of 01˜03 are as follows:

Group 01 02 03 Horizontal viewing field direction 30° 90° 150°

The simplified method above will produce some image jump, but which isacceptable basically and lower the rendering cost.

The inner side of spherical screen adopts special metal reflectingmaterial, internal surface is evenly sprayed to ensure even reflection.

The technique and equipment concerning this invention can be widelyapplied to film industry, which can either be recorded in simulationmode or digital ways, as well, they are applicable to 3D production.

The invention involves many other embodiments, rendering surface as partof curved surface B, projection screen as part of spherical surface,view field angle of rendering surface and projection screen areconsistent.

As for image system rendering model composed of common digital lens, therendered image turn to be distorted, the engendered distortion isrestored by keeping rendering surface unchanged (as curved surface B, orpart of curved surface B), the projection screen is at the rear side ofrendering surface viewing field direction, viewing field direction andangle of rendering surface is consistent with that of projection screen.Subjected to the above said conditions, the invention can be applied insome other ways, for example, projection screen can be hemisphericalsurface or part of it, rendering surface is part of curved surface B.Projection screen can be plane, combination of plane and curved surface,random curved surface or part of it; rendering surface can also bespherical surface, conicoid or part of it.

No matter it is image system or projection system, arrangement asfollows are also available: up-down M layer cameras or projectors, eachlayer contains N cameras or projectors, that is to say, the wholerendering model may include M×N cameras and M×N projectors, M and N canbe any positive integer.

What is claimed is:
 1. A curved film projection system, comprising arendering surface, a projection screen, a real scene rendering model ofimage system, a rendering model of projection system that renders theprojection the image rendered by the rendering model of image system onthe rendering surface, and a projecting device that projects the imagefinally rendered by the rendering model of projection system onto theprojection screen through optical lens. The said projection screen isregarded as the first surface or part of the first surface. The saidrendering surface is regarded as the second surface or part of thesecond surface. The first surface is behind the said second surface,watching from observer's eyes to projection screen. The viewingdirection and angle from observer's eyes to the rendering surface isconsistent with that to the projection screen. The viewing direction andangle from observer's eyes to the rendering surface is consistent withthat to the screen; the said image system rendering model can bereversible with the said projection system model. The said rendered realscene by projection system rendering model, projected to the secondsurface and then to the projection screen through projecting device,exactly restore the distorted image produced by the image systemrendering model.
 2. The curved film projection system as defined inclaim 1, wherein the rendering models of both image system andprojection system respectively comprise cameras and projectors, the viewdirections of which are consistent, two centers coincide, but theoptical paths are reversible.
 3. The curved film projection system asdefined in claim 1, wherein the image system rendering model comprisesup-and-down M-layer digital cameras and each layer contains N cameras.4. The curved film projection system as defined in claim 3, wherein thesaid M is 3, the said N is 7, the said image system rendering modelcontains 21 single digital cameras.
 5. The curved film projection systemas defined in claim 4, wherein angle of the horizontal view field ofeach digital camera is 25.7142857°, and the angle of vertical view fieldis 60°. The viewing direction of all digital cameras follows the samedirection as that of the divided viewing field. Horizontal viewingdirection of each camera is 12.8571°, 38.5714°, 64.2857°, 90°,115.7143°, 141.4286° and 167.1429° respectively.
 6. The curved filmprojection system as defined in claim 3, wherein the said M is 3, thesaid N is 3, the said image system rendering model contains 9 digitalcameras. The angle of horizontal view field of each camera is 60°. Theangle of vertical view field is 60°. Viewing direction of all digitalcameras follow the direction of divided view field. The horizontalviewing direction of each single digital camera in each layer is 30°,90° and 150° respectively.
 7. The curved film projection system asdefined in claim 1, wherein the said projection system rendering modelcomprises upper and lower M-layer digital cameras, each layer of whichcontains N single digital projectors.
 8. The curved film projectionsystem as defined in 7, wherein the said M is 3, the said N is 7, thesaid projection system rendering model contains 21 single digitalcameras.
 9. The curved film projection system as defined in claim 8,wherein the angle of horizontal viewing field of each projection systemrendering model is 25.7142857°, and the angle of vertical view field is60°. The viewing directions of all digital projectors are the same asdivided view field. Horizontal viewing direction of each projector ineach layer is 12.8571°, 38.5714°, 64.2857°, 90°, 115.7143°, 141.4286°and 167.1429° respectively.
 10. The curved film projection system asdefined in claim 7, wherein the said M is 3, the said N is 3, and thesaid projection system rendering model contains 9 cameras. The angle ofhorizontal view field of each projector is 60°. The angle of verticalview filed is also 60°. Viewing direction of all digital projectors arethe same as that of divided view field. The horizontal viewing directionof each digital projector in each layer is 30°, 90° and 150°respectively.
 11. The curved film projection system as defined in claim1, wherein the said first surface is a curved surface, a plane surface,or a combination of plane and curved surface.
 12. The said curved filmprojection system as defined in claim 1, wherein the said second surfaceis sphere or conicoid.
 13. The said curved film projection system asdefined in claims 1 to 11, wherein set a spherical surface, take thevertical section of the sphere, which is round in shape, the saidvertical axis of the section is OZ, divide horizontal viewing field0˜180° of the section into n parts, indicate the n viewing directionswith radial OA1˜OAn, divide the said semicircle diameter evenly into nparts with section points as P0, P1, P2 . . . Pn-1 and Pn, draw n linesas L1, L2, L3 . . . Ln-1 and Ln paralleled to OZ axis cross the said nsection points, then followed with in turn M1, intersection point of OA1and L1, M2, intersection point of OA2 and L2, M3, intersection point ofOA3 and L3 . . . Mn-1, intersection point of OAn-1 and Ln-1, Mn,intersection point of OAn and Ln, connect M0, M1, M2 . . . Mn-1 and Mnto get a curve K, rotate curve K 360° around OZ axis to get curvedsurface B, the said second surface is curved surface B.
 14. A curvedfilm projection method, comprising following steps: A1) the renderingmodel of image system rendering the real scene. A2) the rendering modelof projection system rendering the projection of image rendered by theimage system rendering model on the rendering surface. A3) theprojecting device projecting the finally rendered image of the renderingmodel of projection system onto the projection screen via the opticallens.
 15. The curved film projection method as defined in claim 14,wherein the rendering as mentioned in above A2) of claim 14 adoptsorthogonal rendering.